The present invention relates to machines of the type which include an endless conveyor belt having an upper run sliding on a support surface.
Such structure may be included in a grinding machine, and the present invention is particularly applicable to grinding machines.
In certain types of machine tools, where workpieces are conveyed by a run of a conveyor belt which slides along a supporting surface, it is important to prevent any undesired separation of the belt from the supporting surface along which it slides. Such undesired separation can be caused, for example, by particulate matter which undesirably becomes located between the belt and the support surface on which it slides, or such undesired separation may be caused by excess fluid which becomes situated between the belt and the surface on which the belt is intended to slide. Of course, in the case of particulate matter, undesired scratching of the surface on which the belt slides can occur. However, this undesired separation of the belt from its supporting surface is a possible source of inaccuracy in the machine operations. For example if the machine tool which acts on the workpieces is situated over the belt so that the workpieces move between the belt and the machine tool while conveyed by the belt, the distance between the belt and the machine tool is critical in order to obtain desired accuracy in the machining of the workpieces. Thus, if the machine tool is a rotary grinding wheel having a downwardly directed grinding surface located over the upper surface of the belt which carries the workpieces, if this upper surface does not reliably engage the supporting surface beneath the belt, the belt will be displaced by particulate matter, excess fluid, or the like, closer to the grinding wheel or other machine tool, so that inaccuracies will occur in the machining operations in that the particulate matter, excess fluid, or the like locates the belt and thus the workpieces carried thereby closer to the grinding wheel or the like than would be the case if the undesired separation between the belt and the surface on which it slides did not occur. As a result too much material is cut away from the workpieces during the machining thereof as a result of the location of undesired matter between the belt and the surface on which it slides.
This problem has already been recognized in the art. In order to avoid the drawbacks resulting from undesired separation of the belt from the surface on which it is intended to slide it has already been proposed to wash the surface of the endless conveyor which slidably engages the support with water jets, and it has also been proposed to provide rubber scraper blades which act to dislodge waste material from the conveyor so as to minimize in this way the possibility of inaccuracies in the machining operations such as grinding, for example.
However, these attempted solutions to the problem have not proved to be fully satisfactory in practice. The use of jets of water or the like or rubber scraper blades undesirably complicate the machine tool and such expedients in themselves create undesired problems. Furthermore, because the cleaning operations achieved with such water jets, scraper blades, or the like, take place at a location other than the surface on which the belt slides, it is still possible for undesired matter to become located between the belt and the surface on which it slides prior to cleaning of this matter away from the belt, so that the known attempts to solve the problem cannot be fully relied upon to achieve the desired results.